Rivers of Carbon
Recovering our Rivers – ‘After the Fire’

A project funded by The Caterpillar Foundation to enable Greening Australia, the Upper Murrumbidgee Demonstration Reach and the Australian River Restoration Centre to support landholders in the aftermath of the 2020 fires.

Ngarigo and Ngunawal Country

We are honoured to work on the ancestral lands of the Ngarigo and Ngunawal people, and we recognise their continuing connection with, and knowledge about land, waters and community. We pay our respects to them and their cultures; and to Elders past, present and emerging.
Adapted from: Welcome to Country & Acknowledgement of Country – Creative Spirits

Fire tore through the Bumbalong Valley with the hills burnt right down to the river's edge. Photo: Antia Brademann

“Australia has never seen fires like this… and there are more to come”

– Australian Koala Foundation

Recovering our Rivers – ‘After the Fire’, is a practical, focused response designed to help landholders grapple with the immense damage sustained to their properties as a result of a fire storm, followed by a mass erosion event, which swept through parts of the Upper Murrumbidgee earlier this year.  By supporting landholders through the installation of erosion structures to prevent high amounts of sediment and ash entering the river, the project will provide people with the reassurance that they are not alone in facing the devastation the fires left behind.  The proposed works will also prevent vast amounts of sediment and ash entering the river, smothering fish habitat, reducing water quality and threatening decades of river restoration work.   Recovering our Rivers – ‘After the Fire’ will also be working in areas of the river that were not directly impacted by the fire but, with the advent of rain, are likely to be choked with ash and sediment flowing downstream.  The area we have chosen to work in has a population of nationally endangered Macquarie Perch and Platypus that require protection.

This road crossing will be fixed to prevent sediment from moving into the stream. Photo: Siwan Lovett

Our work in this project will focus on three key activities – erosion control, sediment control through willow removal and revegetation, and the provision of fish habitat.

Emergency erosion control structures

Some of the work to be undertaken will be in reaches of the river directly impacted by the fire and the massive erosion event that followed.  It is here that the majority of the costs in the project will be allocated against the following works

The fire, which impacted the steep and rugged upper Murrumbidgee River corridor just north of Bredbo in February 2020, was so intense that only bare soil remained.  During such events the chemical nature of the soil is altered so that it becomes water repellent, with the lack of vegetation reducing the infiltration capacity of the soil even further.  The rain event which extinguished the fire resulted in a mass erosion event which mobilised ash and sediment, and was assisted by the steepness of the terrain.   New erosion scours, the remobilisation of existing headcuts, and the dumping of massive amounts of gross sediment (sand and ash) in the base of tributary gullies to the river, now pose an ongoing threat to water quality (due to fine sediments and ash) and fish habitat (smothering refuge holes and breeding sites by sand slugs).

Recovering our Rivers – ‘After the Fire’ will address water quality decline by remediating three sites on two properties- a severely scoured gully floor eroding through an alluvial terrace, and a sediment control structure to hold back sediment further up on the same tributary gully and which is at risk of being washed into the river.  We will also treat an erosion headcut on a tributary gully on another property.  These works are a priority, as the catchment still struggles to recover ground cover and there is a high risk of further erosion during a heavy rain event.  Small rain events are showing us that the sand which is currently deposited in the tributary gullies is already being remobilised.

These works will protect priority fish habitat in the upper Murrumbidgee, including two natural populations of threatened native fish – namely Macquarie perch and Murray cod.  The work will also prevent further sediment entering the river which is one of the source catchments of Canberra’s drinking water supply.

Large sediment and ash plumes like this one will be controlled through erosion works. Photo: Siwan Lovett

Sediment control through strategic willow removal

Macquarie perch are an endangered native fish that require good quality water flowing over shallow rock riffles and native riparian habitat. In this stretch of reach works Recovering our Rivers – ‘After the Fire’ will address the increasing infestation of problematic Crack Willows that will eventually smother fish habitat and replace native riparian vegetation. These willows are currently at a level where they can be managed with good cost effectiveness but, if left for any longer, will become more and more difficult to control. Crack Willow are a particularly invasive type of willow which are difficult to control due to their multi-stem growth habit. Fortunately, there are skilled contractors who can effectively stem inject and kill these species while retaining their structure in situ. The infestation is currently at a level where they can be safely left as structural habitat and will break down over a number of years. This work will complement an associated Rivers of Carbon Macquarie perch project where a cluster of landholders either have, or are in the process of, fencing their section of the Murrumbidgee River from stock, installing alternative water sources and planting native vegetation to protect and enhance habitat for native fish and Platypus.  It will complement willow control activities that have been occurring upstream and downstream of the project site.

This stretch of river has had willows removed on one side of the bank. We know Maccas live here, so we will treat the remaining willows and provide fish hotels for habitat as we wait for native revegetation to grow. Photo: Siwan Lovett

Fish hotels and habitat structures

This part of Recovering our Rivers – ‘After the fire’ will work in association with the willow control works being carried out to improve Macquarie perch habitat.  This species requires instream structure in its habitat for protection and is important at all stages of the lifecycle from young of year to mature fish.    Such structure, otherwise known as ‘snags’, is provided by native hardwood debris falling into the river from riverside vegetation.  Snags have historically been removed from our rivers, and the native vegetation which provides a source of snags has been historically cleared. Newly planted vegetation takes many decades before it is large enough to fall in and improve fish habitat.

This project will build and install a fish ‘hotel’ to improve fish habitat for Macquarie perch in the upper Murrumbidgee River.  The project site is just downstream of a breeding site for the species and is the known refuge area for the species.  Habitat improvement is a high priority for the species.  The hotels consist of log crib structures which are submerged into the river and filled with large sized rock.  This provides refuge for small fish from predation.

Erin (DPI Fisheries) releasing a Macca, the fish we will be helping through this project. Photo: Siwan Lovett
Sediment and ash washed down from the hills.- once in the river it smothers fish habitat. Photo: Siwan Lovett

Progress:

Our team (shown in the photo below) of Ian Rayner and Graham Fifield from Greening Australia, along with Antia Brademann from the Upper Murrumbidgee Demonstration Reach and Lori Gould and Siwan Lovett from the Australian River Restoration Centre. We recently spent a day out looking at the sites we will be doing our work. This site is at Dromore where we will be installing fish hotels and doing some willow control.

This great project will be completed by October 2021 so we are hustling!  You can keep in touch with how we are going via our free monthly Australian River Restoration Centre newsletter or by following us on Facebook.

Want to know more about our work on the Bidgee?

The Upper Murrumbidgee River is a special place, with rich biodiversity, cultural heritage and communities keen to protect and restore the social and environmental assets the region contains. Our projects in this stretch of river are varied, and include adventurous volunteering, fish habitat creation, riparian revegetation, erosion control and community engagement.

Read More